Chemicals company Ineos has ordered another two state-of-the-art vessels to transport U.S. shale gas to its facilities in Scotland and Norway.

This will increase the Ineos fleet to eight "Dragon Class" multi-gas carriers.

Ineos is currently building a new ethane import terminal, storage tank and associated infrastructure in Grangemouth, Scotland, to import ethane from the United States. Construction is expected to be completed in 2016. In Rafnes in Norway, a new ethane storage tank and terminal is being built and is on track to be fully operational in 2015.

The new vessels from Evergas will satisfy the demand from Ineos crackers at these two sites, the company said on Tuesday.

Ineos entered into the world's first U.S. ethane export contract in October 2012 when it signed agreements to buy gas from U.S. shale producers and capacity in the Mariner East project.

David Thompson, chief operating officer of Ineos Trading & Shipping, said that the ethane from the United States will be the most competitive feedstock in Europe and is essential to the two plants.

"The two additional 'Dragon Ships' mean we can transport sufficient volumes of ethane to meet the demands of our manufacturing sites and continue to take advantage of significant cost benefits," he added.

According to Ineos, the Dragon Class ships are tailored to meet the specific needs of this project and will provide a flexible solution for ethane supplies, with the option of transporting LNG and LPG as well as petrochemical gases including ethylene.